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MEMS humidity sensor based on phase detection principle and preparation method

A technology of humidity sensor and phase detection, which is applied in the process of producing decorative surface effects, the coupling of optical waveguides, and the manufacture of microstructure devices. It can solve the problems of difficult and accurate measurement of humidity, and achieve low price and zero DC power consumption. , Improve the effect of integration

Pending Publication Date: 2021-11-19
NANJING GAOHUA TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, among conventional environmental parameters, humidity is one of the most difficult to measure accurately
Traditional hygrometers are increasingly unable to meet the actual needs at this stage, so research on new humidity sensors is very necessary

Method used

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  • MEMS humidity sensor based on phase detection principle and preparation method
  • MEMS humidity sensor based on phase detection principle and preparation method
  • MEMS humidity sensor based on phase detection principle and preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] This embodiment provides a MEMS humidity sensor based on phase detection principle, such as Figure 1 ~ Figure 3 As shown, it includes: a CPW transmission line, a substrate 13 , a groove 131 , a buffer medium layer 132 , a MEMS film 2 , a MEMS beam 3 , a moisture sensing layer 4 and a through hole 5 .

[0030] Specifically, the CPW transmission line is arranged horizontally on the substrate 13, including the CPW signal line 1 located in the middle of the substrate 13 and two CPW ground lines 12 located on both sides of the CPW signal line 1, the CPW signal line 1 and the CPW ground line 12 Can be arranged parallel to each other.

[0031] The groove 131 is located on the substrate 13 directly below the CPW signal line 1, the groove 131 is, for example, a U-shaped groove, and the central axis of the groove 131 is parallel to the CPW signal line 1; the surface of the substrate 13 and the groove 131 is provided with a buffer medium layer 132.

[0032] The MEMS beam 3 is a...

Embodiment 2

[0037] The present invention also provides the preparation method of the above MEMS humidity sensor based on the phase detection principle, such as Figure 4-9 shown, including the following steps:

[0038] S10 prepares a substrate, which may be a common semiconductor substrate, such as a silicon substrate, using high-resistance silicon with a resistivity greater than 1 kΩ·cm. The higher the resistance of the silicon substrate, the CPW is made on silicon, the RF signal loss of its transmission is low, and the RF performance will be better. If the external humidity changes cause capacitance changes, the phase change of the RF signal will be more obvious.

[0039] A groove 131 is etched on the substrate, and then a buffer dielectric layer 132 is grown on the substrate by thermal oxidation, such as Figure 5 As shown, wherein the depth of the groove is, for example, 1-10 μm;

[0040]S20 sequentially passes photolithography, evaporation, and lift-off on the buffer medium layer t...

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Abstract

The invention provides an MEMS humidity sensor based on a phase detection principle and a preparation method. The sensor comprises a CPW transmission line which is disposed on a substrate, the CPW transmission line comprises a CPW signal line and CPW ground lines at two sides of the CPW signal line, and the substrate below the middle part of the CPW signal line is provided with a groove; MEMS beams are positioned on the bottom surface of the groove and two side surfaces close to the CPW ground lines; an MEMS film is positioned above the groove and is in contact with the bottom surface of the CPW signal line, and a through hole is formed in the surface of the MEMS film; and a humidity sensing layer is located between the MEMS beams and the MEMS film and fills the internal space of the groove. The humidity of the external environment is sensed by utilizing the water absorption of the humidity sensing layer in the groove, the dielectric constant of the humidity sensing layer can change along with the humidity, the capacitance between the MEMS beams and the CPW signal line is changed, the phase of an RF signal on the CPW transmission line is changed, and the environment humidity can be obtained by measuring the phase of the RF signal.

Description

technical field [0001] The invention relates to the technical field of radio frequency microelectromechanical systems (RF MEMS), in particular to a MEMS humidity sensor based on the principle of phase detection and a preparation method. Background technique [0002] Humidity, usually refers to the content of water vapor in the air, which is used to reflect the dryness and humidity of the atmosphere. Air humidity is directly related to people's daily work, life and production, so the monitoring and control of humidity is becoming more and more important. However, among conventional environmental parameters, humidity is one of the most difficult to measure accurately. The traditional hygrometer has become more and more unable to meet the actual needs at this stage, so the research on new humidity sensors is very necessary. Humidity sensors have been widely used in many fields including national defense aviation, meteorological detection, industrial control, agricultural prod...

Claims

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Application Information

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IPC IPC(8): G01N27/22B81C1/00B81B7/02
CPCG01N27/221G01N27/223G01N27/226B81B7/02B81C1/00015
Inventor 王耀兰之康江洲玮
Owner NANJING GAOHUA TECH
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